The present invention relates to endoscopes of the kind incorporating a beam splitter for direct observation and for joint observation by means of a folded optical system of substantially larger diameter than the endoscope or for connection of a film or television camera to the folded optical system. Hereinafter such an endoscope will be referred to as "of the kind described".
Endoscopic images, which are supplied to the eyepiece of a co-observer by means of a beam splitter and a folded optical system, only occupy a correct horizontal and vertical position in the eye-piece in one particular position of the members of the folded optical system. As soon as any movement of the parts of the optical system is necessary for comfortable observation, deviations from this position occur and the image in the eye-piece is deflected by up to 180.degree. in, for example, an anticlockwise direction so that the observer is no longer in a position to recognise what part of the image is at the top.
To eliminate this disadvantage marks have already been made in two parts of the folded optical system, that is in the eye-piece and lens parts which are made to overlap by swivelling the eye-piece member or by connecting links whereby correct positioning of the image for the co-observer occurs.
It is an object of the invention to provide means whereby the observer is able to recognise the actual position of the image and to adjust the image horizontally and vertically in the observer's eyepiece.